EP 1 437 117 A1 (Cognis France) discloses sinapic acid (=3,5,-dimethoxy-4-hydroxycinnamic acid, =(3,5-dimethoxy-4-hydroxy-phenly)-3-prop-2-enoic acid, =sinapinic acid) and its derivatives as cosmetic ingredients. The derivatives are referenced in claim 15 and in paragraph [0025]: the derivatives obtained according to this paragraph are all derivatives via the acid function of sinapic acid. Derivatives via the 4-Hydroxygroup of the phenyl group or via the alkylene group adjacent to the acid group are not disclosed. EP 1 437 117 also cites the problem of instability for sinapic acid and proposes as solution a microencapsulation.
JP 64-013017 (Pola Chemical Industries) discloses derivatives of 3,5-dimethoxy-4-hydroxycinnamic acid. All the derivatives disclosed are derivatives via the acid function of the sinapic acid. No derivatives of the 4-hydroxygroup or the alkylene group are described.
JP 2004175778 A (Sogo Pharmaceutical Co) discloses cinnamic acid derivatives as cosmetic ingredient. All derivatives disclosed carry a specific group (2) or (3) on the acid moiety of the cinnamic acid. These substances are not encompassed by the substances according to the present invention.
WO 03/027055 A (Pacific Corporation) discloses thymyl or carvacryl esters of 3,4,5-trimethoxy phenyl acetate, 3,4,5-trimethoxy cinnamate or 3,4,5-trimethoxyhydrocinnamate and their use as whitening compositions.
Aim of the invention was to provide substances which can be effectively used for the manufacture of or in cosmetic compositions and which are especially suitable as skin whitener and/or as cosmetic agents against the signs of skin ageing. Of special interest was to provide substances which are chemically stable and can thus be easily incorporated into cosmetic compositions. In addition it is desired that these substances do not, or only to a much lower extent than products known in the market, cause an irritation of the skin onto which it is applied. A further aim of the invention was to provide substances for the manufacture of a medicament for the treatment of disorders related to the pigmentation of the skin. The invention furthermore relates to specific substances.